Unfortunately, cracking is pretty common in concrete, especially during the first 30 days, while itâs curing. There are a number of reasons why concrete cracks. The most common is because concrete shrinks as the excess water evaporates and it hardens. Concrete can also crack if it dries too quickly. Weather conditions â extreme temperatures, rapid temperature changes or conditions that are too wet or too dry â also play a major factor in how well concrete cures. When the width of a crack exceeds 1/4â in width, it is probably time to seek professional assistance.
Knot (unit) The knot (/nÉt/) is a unit of speed equal to one nautical mile (1.852 km) per hour, approximately 1.151 mph. The ISO Standard symbol for the knot is kn. The same symbol is preferred by the IEEE; kt is also common. The knot is a non-SI unit that is accepted for use with the SI.
Confidence votes 8.2K. Slightly greater than 1.15mph A knot, or nautical mile (6076 feet), is about 15% longer than a statute mile (5280). So, if you're traveling at a speed of 20 knots in a motor boat, you simply multiply 20 X 1.15 to get 23 mph. To go from mph to knots, multiply mph by about .87 to get knots.